Cellulose unit



Sept. 11, 1934. I uc s 1,973,571

CELLULOSE UNIT Filed Sept. 26*. 1932 INVENTOR. fr w'rzyJc'rz K A due/E6ATTORNEYS Patented Sept. 11, '1934 UNlTED STATES PATENT OFFICE I. F.Laucks, Inc., tlon of Washington Seattle, Wasln. a corpora- ApplicationSeptember 26, 1932, Serial No. 634,931

6 Claims.

It has beenheretofore discovered that sulphur derivatives of carbonicacid are water resistanceincreasing agents when incorporated withadhesives embodying either animal or vegetable proteins or both.Viscose,.as one of these sulphur derivatives of carbonic acid, has beenproved to be quite eilicient as a water resistance-producing agent whenused with such adhesives.

Now, however, it has been discovered that vis- 10 cose in itself is aneflicient adhesive, when proteins are entirely'absent from thecomposition or present only in minor percentages, when applied to woodand particularly to veneers or used in the manufacture of plywood.

To the accomplishment of the'foregoing and related ends, the invention,then, comprises the features hereinafter fully described, andparticularly pointed out in the claims, the following descriptionsetting forth in detail certain illustrative embodiments of theinvention, these being indicative however, of but a few of the variousways in which the principle of the invention may be employed.

In the annexed drawing:

The sole figure is an enlarged section through a laminated wood unit inaccordance with the invention.

For the purposes of this disclosure the term viscose may be defined toinclude all cellulose xanthogenates. The base material of suchxanthogenates may be cotton, wood pulp, ground wood, wood flour,purified cellulose, oxycellulose, cellulose partially purified, revertedcellulose, seed coats as soya bean seed coats, straw, etc. Thesexanthogenates are injgeneral prepared by treatment of the cellulosicmaterial with caustic soda and with carbon bisulphide. It isparticularly to be noted that the term viscose, as herein used, is notto be restricted to the one product of pure Bevan.

The use of viscose as an adhesive for wood, and particularly forplywood, has been exemplified by me in the following manner:

Cellulosic material is treated with caustic soda solution of ten percent or greater concentration for periods varying from less than onehour to several days, the time of treatment being shortened by heating.When the celluloses and hemicellulose originally described by Messrs.Cross 8:

" ,50 celluloses ofthe material are converted to alkali compounds theexcess caustic solution may be removed. However, it has been discoveredin the course of my experiments that caustic soda in excess of theamount necessary to convert the 5-3 celluloses and hemi-celluloses (ifthe latter are present) into the corresponding alkali compounds, servesto promote the workable life of the xanthogenate resulting aftertreatment of the alkali compounds with carbon bisulphide.

When the alkali cellulosic compounds are converted into xanthogenates(viscoses) by any of the well known methods they are ready to be spreadon wood panels.

Fir veneer spread with cellulose xanthogenate and assembled into 3-plyor 5-ply panels, for example, and subjected to pressure in the ordinaryplywood press, result in fir panels of commercial quality and strengthshowing considerable water resistance. They may be used for commercialpurposes. The product thus manufactured is new in the plywood field andmay be described as a wood product composed of individual wood piecesbound together by a glue of cellulosic derivation. It has the advantagesof ease of handling of materials during manufacture, of such simplicitythat the binder may be made at each individual veneer plant in suchquantities as are desired for immediate use. It has the furtheradvantage of cheapness because of the utilization of cheap forms ofcellulose. It has the further unique property of providing a bond ofcellulosic material for ligno-cellulose material such as wood sheets orblocks. The progressive development of reaction products producesregenerated celluloses and hemi-celluloses. This regeneration ofcelluloses and/or hemi-celluloses on the glue line (in situ) by thenormal process of reversion of cellulose xanthogenates (viscose-s)provides a cellulosic bond for cellulosic material-a cellulosic unit, amuch desired result heretofore unattained. The binding material on theglue line being of the same or very closely allied chemical composition,as well as like physical'properties as the material bound, for examplewood sheets, provides a finished unit of construction which has mostdeclded advantages in avoidance of the destructive effects of strainswhich are set up by unequal expansion and contraction of the severalcomponent parts of the unit (plywood, for example) when such componentparts are of varying chemical composition and unlike physicalproperties. Such contraction and expansion is inevitable in wood units,due to the changes in moisture content which are constantly in progress.When the material operating as the binder for wood sheets, laid asplywood is made with the grain in adjacent sheets running at rightangles each to the other, is of chemical composition closely allied tothe chemical composition of the wood sheets, the degree of expansion orcontraction of the 1m heating of the panels may be performed in thebinding material due to moisture content change will be more nearly thesame as that of the wood sheets bound, than is the case when the binderis of very different composition chemically from the composition of thematerial bound. Thus it 'is shown that my discovery enables themanufacture of laminated structures of cellulosic nature, as for exampleplywood, which are not subject to the undue internal stresses andstrains due to moisture changes and consequently less" subject tosurface checking and cracks in interior plies, which not only weaken theunits but make them less resistant to moisture transfer,

and also in the case of surface checks seriously.

y detracting from an- .less than than two hours to get maximum strengthincreases provided that the temperature of 220 F. is attained in thekiln or heating chamber for at least a portion of the period. If desiredthe ordinary commercial hot press provided the temperatures above namedare attained at the glue lines of the panels. The humidity of the kilnor heating chamber should be maintained at a point suchthat the moisturecontent of the panels is not decreased below 10%, thus avoiding unduechecking of tlie plywood.

Other modes of applying the principle of the invention may be employedinstead of the one explained, change being madeas regards thereaturesherein disclosed, provided the features stated in any of the followingclaims, or the equivalent of such be employed.

What I claim is: 7

1. Unit composed of wood laminations, adjacent laminations beingboundtogether by a substantially co-extensive film of an adhesive of revertedcellulose.

2. Unit composed of wood laminations, adjacent laminations being boundtogether by a substantially co-extensive film of an adhesive ofcellulose xanthogenate. I

-3. Unit composed of wood laminations, adja cent laminations being boundtogether by a substantially co-ex'tensive'film of an adhesive ofreaction products of cellulose xanthogenates.

4. A cellulose unit composed of wood laminations laid with the grain ofeach lamination at right angles to. the grain of the adjacentlamination, adjacent laminations being bound together by a substantiallyco-extensive adhesive film of reverted cellulose.

5. A cellulose unitcomposed of wood laminations laid with the grain ofeach lamination at right angles to the grain of the adjacent lamination,adjacent laminations being bound together by a substantiallyco-extensive film of a cellulose xanthogenate adhesive.

6. A cellulose unit composed of wood laminations laid with the grain ofeach lamination at right angles to the grain of the adjacent lamination,adjacent laminations being bound together by a substantiallyco-extensiv'e adhesive film comprising the reaction products ofcellulose xanthogenate.

' IRVING FINK LAUCKS.

